民勤绿洲—荒漠过渡带微区水分过程研究

发布时间：2018-07-06 16:28

本文选题：微区 + 土壤水分　；参考：《甘肃农业大学》2015年硕士论文

【摘要】：选择甘肃民勤绿洲荒漠过渡带广泛分布的微区(白刺沙堆丘间低地微区、粘土沙障+梭梭固沙林内微区及粘土平地微区)作为研究对象,通过查阅降水资料、野外调查、土样采集、人工模拟降雨及跟踪观测土壤含水量,研究微区土壤入渗过程及水分时空动态变化,结果表明:(1)研究区降水量在年际间差异较小且服从正态分布。降水主要集中于7~9月,多年月均降水量变幅大,四季降水分布差异大。降水多发生于夜间,不考虑月份变化,昼夜间降水量相关性显著且呈正比。大雨量级相比小雨量级其降水次数年际差异大,降水次数随雨量级数增大而减小。(2)微区径流特点:汇离短、汇流面小、流量小;产生形式:坡面径流、树干径流;产流过程:蓄渗阶段、坡面漫流阶段。三种类型微区积水区与产流区土壤粒度:白刺沙堆丘间低地细砂粒含量在积水区和产流区各层中所占比例最大,0~10 cm土壤表层积水区粘、粉粒含量远小于产流区。粘土平地积水及产流区土壤组成以粗、细砂粒为主,粘粒含量在各对应层产流区都好于积水区。粘土沙障+梭梭固沙林以粗砂粒为主,结构较为单一。(3)粘土沙障+梭梭固沙林和白刺沙堆丘间低地微区雨强与径流量关系呈一定的线性关系。(4)27.4 mm降雨结束后,粘土沙障+梭梭固沙林内微区核心、过渡和边缘区土壤水分在0~14 h入渗较快;14~86 h明显下降;86 h后入渗很少。白刺沙堆丘间低地微区0~14 h入渗较快(过渡区边缘区核心区),但远小于粘土沙障+梭梭固沙林三区结果;14~74 h,下渗速率变缓;74~254 h,三区下渗依旧持续;至254h其入渗深度小于粘土沙障+梭梭固沙林内三区所得结果。(5)降水结束后三区0~20 cm层土壤水分:粘土沙障+梭梭固沙林0~8 h内损失(核心区过渡区产流区)较小;8~86 h损失较大;86~254 h,三区该层土壤水分损失速率变缓。白刺沙堆丘间低地0~14 h损失速率(核心区边缘区过渡区)较小;14~74 h损失过程与粘土沙障+梭梭固沙林8~86 h结果相似,土壤水分散失明显(核心区边缘区过渡区);74~254 h散失依旧持续,速率变缓,土壤最终含水量:核心区边缘区过渡区。(6)两类微区(粘土沙障+梭梭固沙林和白刺沙堆丘间低地)所设置不同降雨梯度微型蒸渗仪中一天的水分散失过程基本相似。两类微区三区水分蒸发过程具有相似性,散失量:边缘区过渡区核心区。两类型微区在整个实验过程中每天蒸发:15 mm降水量对应蒸发量10 mm降水量对应蒸发量5 mm降水量对应蒸发量。(7)27.4 mm降雨前期两类型微区三区在0~140 cm垂直剖面上土壤水分呈下高上低梯度分布。粘土沙障+梭梭固沙林内微区最大入渗深度:核心区80 cm,过渡及边缘区为60 cm;白刺沙堆丘间低地:核心区40 cm,过渡、边缘区为60 cm。粘土沙障+梭梭固沙林内微区三区土壤水分动态分三层次:低值层,都在20 cm左右;次活跃层,核心区20~80 cm,过渡及边缘区20~60 cm;稳定层,核心区80~140 cm,过渡及边缘区60~140 cm。白刺沙堆丘间低地:低值层,核心区0~15 cm、过渡区0~20 cm、边缘区0~20 cm;水分活跃层,核心区15~30 cm、过渡区20~40 cm、边缘区为20~60 cm;土壤水分稳定层:核心区30~140 cm、过渡区40~140 cm、边缘区60~140 cm。(8)三种类型微区不同区域内植物群落组成结构简单,种类少。白刺沙堆丘间低地及粘土沙障+梭梭固沙林微区内建群植被逐渐退化,以黄花矶松和红砂为主的浅根性灌木和以画眉草、虎尾草和五星蒿为主的草本植被的进入,原有植被群落最终演替方向:乔木-乔灌草-灌草。
[Abstract]:The microarea widely distributed in the desert transition zone of Minqin oasis, Gansu, is selected as the research object. As the research object, the clay sand barrier + Haloxylon ammodendron sand fixation forest micro area and the clay flat micro area are used as the research object. By consulting the precipitation data, field investigation, soil sample collection, artificial rainfall and tracking the soil moisture content, the infiltration of soil in the micro area is studied. The results show that: (1) the precipitation in the study area is smaller and obeys the normal distribution in the interannual. The precipitation is mainly concentrated in 7~9 months, the average precipitation varies greatly in the year and month, the distribution of precipitation in the four seasons is large. The precipitation occurs at night and does not consider the change of month. The correlation of day and night precipitation is significant and positive ratio. The precipitation times are different with the magnitude of precipitation, and the number of precipitation decreases with the increase of rainfall series. (2) the characteristics of micro runoff: short sink, small confluence surface and small flow; production form: slope runoff, trunk runoff; flow process: infiltration stage, sloping flow stage. Soil granularity in three types of micro area water area and runoff region: white thorn sand The proportion of the low ground fine sand particles in the lower hilly area is the largest in the accumulated water area and each layer of the runoff producing area, and the 0~10 cm soil surface water area is sticky and the powder content is far smaller than that in the runoff producing area. The sand grain is the main structure. (3) there is a linear relationship between the rain strength of the clay sand barrier + Haloxylon ammodendron sand forest and the white thorn sand pile. (4) after the 27.4 mm rainfall, the clay sand barrier + Haloxylon ammodendron sand fixation forest is the core, the soil moisture in the transition and marginal areas is rapidly infiltrated in the 0~14 h, and the 14~86 h decreases obviously; 86 h after the entry. The infiltration of 0~14 h in the lowland micro area of the white thorn sand pile is faster (the core area of the transition zone), but it is far less than the three zone of clay sand barrier + Haloxylon ammodendron sand forest; 14~74 h, the infiltration rate slows down; 74~254 h, the infiltration of the three region remains continuous; to 254h, the infiltration depth is less than the three regions in the clay sand barrier + Haloxylon ammodendron sand fixation forest. (5) after precipitation over the end of precipitation. Soil moisture in the three 0~20 cm layer: clay sand barrier + Haloxylon ammodendron sand fixation forest 0~8 h loss (the transition zone of core region) is smaller; 8~86 h loss is larger; 86~254 h, the three zone soil moisture loss rate slows. The low 0~14 h loss rate (the transition zone in the core region of the core region) is smaller, 14~74 h loss process and clay sand barrier + Haloxylon ammodendron. The results of 8~86 h in sand fixation forest are similar, the soil moisture loss is obvious (the transition zone in the periphery of the core region); the 74~254 h dispersion continues, the rate is slow, the final soil moisture content is the transition zone in the marginal zone of the core area. (6) one day in the two kind of micro area (clay sand barrier + Haloxylon ammodendron sand forest and white thorn sand pile low land) The water evaporation process is similar. The evaporation process of water evaporation in the two kind of micro area three regions is similar, and the loss amount: the core area of the transition zone in the marginal zone. The two types of microregions evaporate in the whole experiment process, 15 mm precipitation corresponds to 10 mm of evaporation and 5 mm of evaporation to the evapotranspiration. (7) two types of 27.4 mm in the early period of rainfall. The soil moisture in the three area on the vertical section of the 0~140 cm is lower and lower gradient. The maximum infiltration depth in the clay sand barrier + Haloxylon ammodendron sand fixation forest: the core area is 80 cm, the transition and the marginal zone is 60 cm; the white thorn sand pile is low in the hilly area: the core area is 40 cm, the transition is the 60 cm. clay sand barrier + Haloxylon ammodendron sand fixation forest soil moisture dynamic score in the three region. The three level: the low value layer is around 20 cm; the secondary active layer, the core area 20~80 cm, the transition and the marginal zone 20~60 cm; the stable layer, the core region 80~140 cm, the transition and the marginal zone 60~140 cm. white thorns dune lowland: the low value layer, the 0~15 cm in the core region, the transitional zone 0~20, the marginal zone, the core region, the transition zone, the edge The area is 20~60 cm, and the soil water stable layer: the core region 30~140 cm, the transition zone 40~140 cm, the marginal region 60~140 cm. (8), the plant community structure is simple and the species are few in the three types of micro regions. Herbaceous vegetation dominated by sexual shrubs and turtgrass, tiger tail and Artemisia Artemisia, and the final succession direction of the original vegetation communities: arbor, shrub, grass and shrub.
【学位授予单位】：甘肃农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S152.7

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